Consumers have long claimed to be more virtuous than they are. Retailers called it the “30:3 phenomenon” – 30 per cent of purchasers told pollsters that they thought about workers’ rights, animal welfare and the state of the planet when they decided what to buy, but sales figures showed that only 3 per cent of them acted on those thoughts.

Now, however, retailers are behaving as if consumers mean it. In the UK, J. Sainsbury is selling only bananas with the Fairtrade label, which guarantees a decent income to the grower. Marks and Spencer is stocking only Fairtrade coffee and tea and is buying a third of the world’s supply of Fairtrade cotton. In the US, Dunkin’ Donuts has decided to sell only Fairtrade espresso coffee in its North American and European outlets. Even Wal-Mart, the campaigners’ favourite target on everything from employment rights to destroying mom and pop stores, has devoted itself to a range of “sustainability” projects.